This invention relates to power-driven toothbrushes.
Conventional power-driven toothbrushes are usually driven by electric motors. The size of the motor determines the frequency of vibration of such toothbrushes. A large enough motor must be used to achieve a high enough frequency of vibration to clean teeth quickly and effectively. Such motors expend significant amounts of energy. As a result these toothbrushes are bulky and heavy, the battery lifetime is short and the service life of the toothbrush is reduced.
According to the present invention there is provided a power-driven toothbrush comprising a brush head mounted on a brush handle for vibratory movement relative thereto, a vibration transmitting arm extending between said handle and said head and a vibration actuator located within the handle, said vibration transmitting arm including a magnet located within the handle and the actuator including a solenoid adjacent said magnet and means for supplying AC current to the solenoid at a frequency which is the same as the resonant frequency of the vibration transmitting arm.
Accordingly, the present invention provides a power-driven toothbrush having a brush which vibrates at a high enough frequency to clean teeth quickly and effectively by causing the vibration transmitting arm to vibrate at its resonant frequency, thereby minimizing power consumption and extending the service life of the toothbrush.
Preferably, the means for supplying AC current to said solenoid includes a printed circuit board.
Preferably, the frequency of the AC current delivered to the solenoid and the natural frequency of the vibration transmitting arm are in the range of 100-300 Hz
Preferably the means for supplying AC current include an internal or external power supply providing AC current. Alternatively, the means for supplying AC current include an internal or external power supply providing DC current, which is converted to AC current by the printed circuit board.